METHOD FOR ADAPTING THE VOLUME FLOW

Abstract

A method for operating a conveying device for an aqueous urea solution in a motor vehicle, having a pump for conveying the aqueous urea solution, wherein the aqueous urea solution is conveyed from a tank along a pressure line to an injector, wherein the injector is arranged on an exhaust gas line and is designed to inject the aqueous urea solution into the exhaust gas line. The conveying speed of the pump is controlled depending on the opening operations and closing operations of the injector and/or the pressure conditions resulting therefrom in the conveying section between the pump and the injector.

Claims

1.-8. (canceled)

9. A method for operating a conveying device for an aqueous urea solution in a motor vehicle, having a pump configured to convey the aqueous urea solution, conveying the aqueous urea solution from a tank along a pressure line to an injector; arranging the injector on an exhaust gas line; injecting the aqueous urea solution into the exhaust gas line; and controlling a conveying speed of the pump depending on opening operations and closing operations of an injector and/or pressure condition resulting therefrom in a conveying section between the pump and the injector.

10. The method as claimed in claim 9, wherein a speed of the pump and thus a conveying volume per unit of time is coupled to the opening operations of the injector.

11. The method as claimed in claim 10, wherein, just before opening of the injector, at a same time as the opening of the injector, or just after the opening of the injector, the speed of the pump is increased.

12. The method as claimed in claim 9, wherein a pressure level within the pressure line is detected from the conveying device to the injector, wherein the conveying speed of the pump is increased depending on a detection of a pressure drop.

13. The method as claimed in claim 9, wherein a current with which the injector is energized for opening is detected, wherein the conveying speed of the pump is increased depending on a strength of the current applied to the injector.

14. The method as claimed in claim 9, wherein the conveying speed of the pump during a time over which the injector is open is independent of a conveying volume required for exhaust gas post-treatment.

15. The method as claimed in claim 9, wherein the conveying speed of the pump, which is increased whilst the injector is open, is reduced again as soon as a closing operation of the injector is identified, shortly before the injector is closed, or with a defined delay relative to the closing operation of the injector.

16. The method as claimed in claim 9, wherein a plurality of injectors are provided, wherein a volume flow conveyed by the pump, during an opening of an injector or a plurality of injectors, is increased for each of the opened injectors by a volume flow specific to each respective injector.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The invention is further explained below with reference to a drawing, In the drawing:

[0030] The FIGURE is a graph illustrating the volume flow conveyed by the conveying device with use of the method according to the invention.

DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS

[0031] The FIGURE shows a graph that specifies the state of the injector in the lower part 1. State “0” denotes the closed injector, and state “1” denotes the open injector. The time is plotted along the X axis, and a plurality of opening operations and closing operations are shown.

[0032] In addition, a graph 2 is shown, which likewise shows the time on the X axis, wherein the volume flow of the aqueous urea solution which is conveyed by the pump is plotted along the Y axis. The volume flow is composed of different partial volume flows 3, 4, which in part remain constant over time.

[0033] The uppermost component 5 of the volume shows the volume flow, which is conveyed additionally by the pump depending on the opening state of the injector. The component which is conveyed additionally at the time of opening of the injector (state of the injector changes from “0” to “1”) by the increase of the pump speed is denoted by reference sign 6. This component 6 is not constant over the course of time, but is increased in a temporally delimited manner in accordance with the opening and the closing of the injector.

[0034] The volume flow consisting of the partial volume flows 3, 4 and the component of the volume flow 5 when the injector is closed corresponds to the normally required volume flow in order to convey the required amount of aqueous urea solution. The component denoted by reference sign 6 corresponds to the volume flow that is additionally required by the increase according to the invention of the speed of the pump.

[0035] Lastly, the required amount of aqueous urea solution is injected by the injector into the exhaust gas line or the exhaust gas tract, and substantially only the pressure fluctuation in the pressure line is counteracted by the temporary increase of the volume flow through the pump.

[0036] The FIGURE is in particular not of a limiting nature, and serves for illustrating the concept of the invention.

[0037] Thus, while there have shown and described and pointed out fundamental novel features of the invention as applied to a preferred embodiment thereof, it will be understood that various omissions and substitutions and changes in the form and details of the devices illustrated, and in their operation, may be made by those skilled in the art without departing from the spirit of the invention. For example, it is expressly intended that all combinations of those elements and/or method steps which perform substantially the same function in substantially the same way to achieve the same results are within the scope of the invention. Moreover, it should be recognized that structures and/or elements and/or method steps shown and/or described in connection with any disclosed form or embodiment of the invention may be incorporated in any other disclosed or described or suggested form or embodiment as a general matter of design choice. It is the intention, therefore, to be limited only as indicated by the scope of the claims appended hereto.